Check if the following are available in your Atlas_Core module. If not, do the steps below.
Create a brand new empty project using Mendix 10,
export the Atlas and Atlas_Filled, and import to your project.
Could you also provide some screenshots of the CSS that is applied to the button and span classes of your invisible icons?
And, just to be sure, there is no specific class set in the Appearance tab of your DataGrid?
Had the same problem. Deleting Atlas Core from Marketplace modules and reinstalling it from the marketplace solved the problem.
You can try that.